A South Korean mother has been arrested for allegedly killing her three-year-old son while she was tired from internet game-playing, police said.

The death is the latest of several cases related to computer game addiction in one of the world's most wired societies.

Kim, 27, played online games for about 10 hours a day, police said, adding her neighbours described her house as "like a trash site" where her two children were left crying for hours.

Police in the midwestern city of Cheonan said Kim, who also has a one-year-old son, beat the three-year-old and strangled him after he disturbed her by urinating on the floor and crying.

"She said she was so mad at him because she was about to take some rest after playing online games for four hours in the morning," a city police spokesman said, describing the woman as addicted to game-playing.

Kim left the boy's body in the house for three days and her in-laws reported the death to police.

She mostly played online card games and those involving the raising of virtual pets, the spokesman said, adding she had no history of mental disorder.

The government estimates the number of web addicts at about two million in a nation of about 50 million. From next year, it will offer free software to people at risk, to limit the time they spend on the web.

Last month, a 15-year-old boy committed suicide after killing his mother for scolding him over excessive playing of computer games.

In May, a 41-year-old man was sentenced to two years in jail after he and his wife left their baby daughter to die of malnutrition while raising a "virtual child" on the internet.

In February, a 32-year-old man died after reportedly playing games for five days with few breaks.